Multi-Stationed Continuous Electro-Polishing System

ABSTRACT

A multi-stationed continuous electro-polishing system includes an electrolysis tank, a driving mechanism, electrode plates and a power supply. The electrolysis tank is filled with electrolyzing liquid. The driving mechanism is placed in the electrolysis tank for driving a metal strip into and out of the electrolysis tank. Each of the electrode plates is placed at an adjustable gap from the metal strip in the electrolysis tank. The power supply includes a positive electrode connected to the metal strip and a negative electrode connected to all of the electrode plates.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a multi-stationed continuouselectro-polishing system and, more particularly, to a continuouselectro-polishing system with multiple stations in each of which the gapbetween an electrode plate and a common metal strip is adjustable toadjust current density to reduce the roughness of the surface of themetal strip fast and evenly.

2. Related Prior Art

There are various methods for treating a surface of a large, thin metalsheet. To reduce the roughness of the surface, conventional methods aremainly direct contact processes such as grinding and contact polishing.However, the direct contact processes would entail two problems whenthey are used to treat a metal sheet that is less than 0.5 mm thick. Atfirst, the metal sheet might be damaged. Secondly, the metal sheet mightsuffer residual stress.

Alternatively, the surface treatment of the metal sheet may be executedin an electrochemical or complicate manner. Electrochemistry isconducted at constant intensity since only one station is used and thegap between an electrode plate and the metal sheet is constant. Theoperation is therefore simple but it is difficult to effectively reducethe roughness of the surface of the metal sheet.

As described above, there is only an electrode plate connected to thenegative electrode of a power supply while the metal sheet iselectrically connected to the positive electrode of the power supply.With only one electrode plate, the electrochemistry is conducted at theconstant intensity. To quickly process the large metal sheet in a longreaction tank, the operative parameters are confined in a small range,and it is difficult to effectively reduce the roughness of the surfaceof the large metal sheet. For continuous surface treatment of the metalsheet, there is a serious problem with the evenness. For example, in anelectro-polishing process, the large, if thin metal sheet is fed atspeed of 1 m/min, and each point of the surface of the metal sheet istreated for 3 min, an electro-polishing tank must be 3 meters long. Themorphology of the surface of the metal sheet varies in such length. Asthe gap between the single electrode plate and the metal sheet isconstant, the electrochemistry is conducted at the single constantintensity. The intensity cannot be adjusted corresponding to thechanging morphology of the surface of the metal sheet. Hence, theoperative parameters are confined in a narrow range, and the roughnessof the surface of the metal sheet cannot be reduced effectively if thereis a bubble on the surface of the metal sheet.

The present invention is therefore intended to obviate or at leastalleviate the problems encountered in prior art.

SUMMARY OF INVENTION

It is the primary objective of the present invention to provide anefficient and effective continuous electro-polishing system for treatinga surface of a large metal strip.

To achieve the foregoing objectives, the continuous electro-polishingsystem includes an electrolysis tank, a driving mechanism, electrodeplates and a power supply. The electrolysis tank is filled withelectrolyzing liquid. The driving mechanism is placed in theelectrolysis tank for driving a metal strip into and out of theelectrolysis tank. Each of the electrode plates is placed at anadjustable gap from the metal strip in the electrolysis tank. The powersupply includes a positive electrode connected to the metal strip and anegative electrode connected to all of the electrode plates.

In an aspect, the electrolysis tank includes nozzles each placed betweentwo adjacent ones of the electrode plates in the electrolysis tank forproviding a jet to wash the metal strip of bubbles that occur in theelectro-polishing.

In another aspect, the electrolyzing liquid is solution of acid selectedfrom the group consisting of sulfuric acid, phosphoric acid, glycerol,nitric acid, hydrochloric acid, lactic acid, citric acid, chromic acid,phosphorous acid, and organic acid.

In another aspect, the driving mechanism includes two small rollers, twolarge rollers and two driving rollers. The small rollers are placed inthe electrolysis tank near two ends. Each of the large rollers is placedin a respective one of the small rollers in the electrolysis tank. Eachof the driving rollers is placed outside the electrolysis tank, near arespective one of the large rollers.

In another aspect, the metal strip is 0.5 mm to 0.005 mm thick and henceflexible.

In another aspect, the power supply operates in a continuous manner.

In another aspect, the power supply operates in an intermittent manner.Other objectives, advantages and features of the present invention willbe apparent from the following description referring to the attacheddrawings.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will be described via detailed illustration of thepreferred embodiment referring to the drawings wherein:

FIG. 1 is a cross-sectional view of a multi-stationed continuouselectro-polishing system according to the preferred embodiment of thepresent invention;

FIG. 2 is an enlarged view of a portion of the multi-stationedcontinuous electro-polishing system marked with “a” shown in FIG. 1; and

FIG. 3 is an enlarged view of another portion of the multi-stationedcontinuous electro-polishing system marked with “b” shown in FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIGS. 1 through 3, there is shown an efficient andeffective continuous electro-polishing system according to the preferredembodiment of the present invention. The continuous electro-polishingsystem includes at least one electrolysis tank 1, a driving mechanism 2,a metal strip 3, multiple electrode plates 4 and a power supply 5.

The electrolysis tank 1 is filled with electrolyzing liquid 11. Theelectrolyzing liquid 11 is solution of sulfuric acid, phosphoric acid,glycerol, nitric acid, hydrochloric acid, lactic acid, citric acid,chromic acid, phosphorous acid, or any proper organic acid. Theelectrolysis tank 1 includes multiple nozzles 12 placed therein. Each ofthe nozzles 12 is preferably placed between two adjacent ones of theelectrode plates 4.

The driving mechanism 2 includes at least two small rollers 21 placed inthe electrolysis tank 1, at least two large rollers 22 placed above theelectrolysis tank 1, and at least two driving rollers 23 placed abovethe electrolysis tank 1. Each of the small rollers 21 is placed near arespective one of two ends of the electrolysis tank 1. Each of the largerollers 22 is placed near a respective one of the small rollers 21. Eachof the driving rollers 23 is placed near a respective one of the largerollers 22.

The metal strip 3 is moved into and the out of the electrolysis tank 1by the driving mechanism 2. The metal strip 3 includes a surface 31 inneed of polishing. The metal strip 3 is about 0.5 to 0.005 mm thick andhence flexible.

The electrode plates 4 are placed in the electrolysis tank 1. There isan electrolysis gap 41 between each of the electrode plates 4 and thesurface 31 of the metal strip 3. The electrolysis gaps 41 are differentfrom one another.

The power supply 5 of course includes a positive electrode 51 and anegative electrode 52. The positive electrode 51 is electricallyconnected to the metal strip 3. The negative electrode 52 iselectrically connected to all of the electrode plates 4. The powersupply 5 may supply electricity in a continuous or intermittent manner.

In operation, by the smaller rollers 21, the large rollers 22 and thedriving rollers 23 of the driving mechanism 2, the metal strip 3 ismoved into and out of the electrolysis tank 1. The elevation of themetal strip 3 in the electrolysis tank 1 is determined by the smallrollers 21. The power supply 5 is turned on to produce a current thatflows through the positive electrode 51, the metal strip 3, theelectrolysis liquid 11, each of the electrode plates 4 and the negativeelectrode 52, thus executing the electrolysis. Accordingly, the metalstrip 3 is electro-polished by the electrolyzing liquid 11 contained inthe electrolysis tank 1.

By adjusting the elevation of an electrode plate 4 relative to the metalstrip 3 in the electrolysis tank 1, adjusted is the electrolysis gap 41between the electrode plate 4 and the metal strip 3, i.e., between thenegative electrode 52 and the positive electrode 51. The larger anelectrolysis gap 41 is, the higher the resistance is therein. Incompliance with the Faraday's law, the higher the resistance is, thelower the current density is. Preferably, the first electrolysis gap 41is set to be smaller than the second electrolysis gap 41 that is set tobe smaller than the third electrolysis gap 41. Hence, the currentdensity in the first electrolysis gap 41 is higher than the currentdensity in the second electrolysis gap 41 that is higher than thecurrent density in the third electrolysis gap 41. The electro-polishingof the metal strip 3 gets less intense as the metal strip 3 is movedthrough the first, second and third electrolysis gaps 41, and this isdesired as the roughness of the metal strip 3 gets lower. Hence, thereis a large process window, and the quality of the electro-polishing ofthe surface 31 of the metal strip 3 is good.

As mentioned above, each of the nozzles 12 is placed between twoadjacent ones of the electrode plates 4 in the electrolysis tank 1. Eachof the nozzles 12 sends a jet of electrolyzing liquid. The jets areuseful for washing the metal strip 3 of bubbles that occur and attach tothe metal strip 3 because of the electro-polishing, thus removingdefects such as recesses or bosses from the metal strip 3. That is, thejets reduce bubble-incurred shielding and enhance the electro-polishing.

Referring to FIGS. 2 and 3, there is shown the morphology of the surface31 of the metal strip 3 in an enlarged scale. Referring to FIG. 2,before the electro-polishing, the roughness of the surface 31 of themetal strip 3 is high, i.e., the surface 31 of the metal strip 3includes many sharp peaks 311. In the electro-polishing, the charge ismore intense at the peaks 311 than in the other regions of the surface31 of the metal strip 3. That is, the electro-polishing at the peaks 311is more intense than in the other regions of the surface 31 of the metalstrip 3. Accordingly, layers of metal at the peaks 311 are thicker thanlayers of metal in the other regions of the surface 31 of the metalstrip 3.

Hence, referring to FIG. 3, the peaks 311 disappear after theelectro-polishing.

As described above, in the multi-stationed continuous electro-polishingsystem, the electrolysis gap 41 between each of the electrode plates 4and the surface 31 of the metal strip 3 is adjustable independent of theother electrolysis gaps 41. The current density gets higher as the metalstrip 3 is moved through the electrolysis gaps 41. Hence, theelectro-polishing gets less intense as the roughness of the surface 31of the metal strip 3 gets lower. Thus, the electro-polishing can beexecuted on a large metal strip effectively and efficiently, and thequality of the surface 31 of the metal strip 3 is even and good. Theelectro-polished metal strip 3 can be used in a thin-film solar cell,flat panel display or a reflector.

The present invention has been described via the detailed illustrationof the preferred embodiment. Those skilled in the art can derivevariations from the preferred embodiment without departing from thescope of the present invention. Therefore, the preferred embodimentshall not limit the scope of the present invention defined in theclaims.

1. A multi-stationed continuous electro-polishing system including: an electrolysis tank 1 filled with electrolyzing liquid 11; a driving mechanism 2 placed in the electrolysis tank 1 for driving a metal strip 3 into and out of the electrolysis tank 1; electrode plates 4 each placed at an adjustable gap 41 from the metal strip 3 in the electrolysis tank 1; and a power supply 5 includes a positive electrode 51 connected to the metal strip 3 and a negative electrode 52 connected to all of the electrode plates
 4. 2. The multi-stationed continuous electro-polishing system according to claim 1, wherein the electrolysis tank 1 includes nozzles 12 each placed between two adjacent ones of the electrode plates 4 in the electrolysis tank 1 for providing a jet to wash the metal strip 3 of bubbles that occur in the electro-polishing.
 3. The multi-stationed continuous electro-polishing system according to claim 1, wherein the electrolyzing liquid is solution of acid selected from the group consisting of sulfuric acid, phosphoric acid, glycerol, nitric acid, hydrochloric acid, lactic acid, citric acid, chromic acid, phosphorous acid, and organic acid.
 4. The multi-stationed continuous electro-polishing system according to claim 1, wherein the driving mechanism 2 includes: at least two small rollers 21 placed in the electrolysis tank 1 near two ends; at least two large rollers 22 each placed in a respective one of the small rollers 21 in the electrolysis tank 1; and at least two driving rollers 23 placed outside the electrolysis tank 1 near a respective one of the large rollers
 22. 5. The multi-stationed continuous electro-polishing system according to claim 1, wherein the metal strip 3 is 0.5 mm to 0.005 mm thick and hence flexible.
 6. The multi-stationed continuous electro-polishing system according to claim 1, wherein the power supply 5 operates in a continuous manner.
 7. The multi-stationed continuous electro-polishing system according to claim 1, wherein the power supply 5 operates in an intermittent manner. 